1. Field of the Invention
The present invention relates to a light reflector for use in a reflective type of liquid-crystal display, which makes use of the internal reflection in a prism to reflect light.
2. Description of the Related Art
In above-noted type of light reflector for a reflective-type liquid-crystal panel, there is the need to have high intensity, meaning that the light reflectivity is high, the need for good diffusion characteristics, so that uniform light is diffused in a desired direction, and the need for high contrast.
In the case of a reflective-type liquid crystal display 1, as shown in FIG. 5, on the observation side with respect to the liquid-crystal display element 2, a surface material 3 is disposed, this surface material 3 having the effects of preventing glare and reflection, so that light does not shine from the surface of the liquid-crystal display 1, and on the reverse side of the liquid crystal display 1, a matte reflective material 4 is disposed, this matte reflective material 4 having a matte-type finish with minute vertical unevenness on its reflecting surface.
A PET (polyethylene terephthalate) film that has a matte-finished film surface resin, or a PET film onto the surface of which is applied a matte paint layer having minute particles is used as the above-noted matte reflective material 4, a light-reflective layer is further formed thereon by vacuum deposition of a metal such as aluminum.
In the above-noted reflective type of liquid-crystal display 1, as shown in FIG. 5, while the incident light that is reflected at the matte reflective material serves as the light (reflected light) for the display, part of the incident light is reflected at the surface material 3 or the liquid-crystal element 2, this representing a wasteful reflection of light.
When the above-noted reflection occurs, because the reflective surfaces of the matte reflective material 4 and the surface material 3, for example, are mutually parallel, the angle of reflection .alpha. of the display light and the angle of reflection .beta. at the surface material 3 are equal, so that he display light and surface reflected light rays are parallel. In the above-noted, the term angle of reflection is not the angle of reflection that the light actually makes with the surface, but rather the apparent angle of reflection with respect to the display surface of the liquid-crystal display.
As a result of the above, if observation is made from the direction of travel of the display light, the display surface appears the brightest. However, because that is also the direction of travel of the surface-reflected light, external light sources will appear on the display surface, making this the direction with the most display glare. For this reason, there is the problem that the direction from which the display appears the brightest is also the direction in which the reflected light is the strongest, thereby making the display difficult to view.
Because of the above-noted problem, there is a reflective-type liquid-crystal display 5, such as shown in FIG. 6, in which the angle of reflection .alpha.1 of the display light and the angle of reflection .beta.1 of the surface-reflected light are made to be different.
The reflective-type liquid-crystal display 5 of FIG. 6 has a sawtooth-shaped reflective material 6 in place of the matte reflective material 4 of the reflective-type liquid-crystal display 1 of FIG. 5.
The cross-sectional shapes on the reflective surface of the sawtooth-shaped reflective material 6 are those of scalene triangles, the surface thereof that faces the liquid-crystal display element 2 being formed as a light-reflective surface by, for example, the vacuum deposition of a metal such as aluminum.
In contrast to the arrangement shown in FIG. 6, because the surface of this type of sawtooth-shaped reflective material 6 is not parallel with respect to the display surface, the angle of reflection .alpha.1 of the display light and the angle of reflection .beta.1 of the surface-reflected light are mutually different, so that the display light and the surface-reflected light travel in different directions.
In the above-noted reflective-type liquid-crystal display 5, however, because the sawtooth-shaped reflective material 6 has a mirror-like reflective surface, there is absolutely no diffusion of light at the reflective surface and, depending upon the direction of external light, the direction in which the display appears bright is limited to an extremely narrow angle range.
Accordingly, it is an object of the present invention, in consideration of the above-described drawbacks, to provide a light reflector for use in a reflective-type liquid-crystal display that has a wide range of viewing angle, without interference from surface-reflected light, and with a bright appearance over a wide angle.